Signs of Heat (oestrus) in Ruminants

Heat or oestrus is the period when the female will accept the male and mate. There are signs which mark oestrus in all ruminants. Recognising when the female is on heat means you will know when to put her with the male or use artificial insemination.

The female reproductive system consists of two ovaries and a womb. Every so often the ovaries produce very small eggs (ova). The time when this happens is called heat or oestrus. Cattle and buffalo regularly come into heat all year round. Most sheep and goats come into heat at a particular time of the year (breeding season).

When do animals come into heat for the first time?

Animals come into heat when they reach puberty. This occurs at different ages in the different ruminants:

  •  Well fed cows and buffalo come into first heat at 10 – 20 months of age.
  • Sheep and goats come into first heat between 6 – 12 months of age.

The duration of heat is very short.

  • In cows and buffalo it lasts for less than a day.
  • In goats heat lasts for 1 – 3 days.
  • In sheep heat lasts for 1 – 2 days.

A healthy animal which was not mounted by a male or given artificial insemination will come back into heat. Cattle and buffalo cows will come into heat after 3 weeks (give or take a day or two), and female goats and sheep will come back into heat after 17 days (give or take a day or two).

The Female which does not come into Heat

The female may not show signs of heat because she is too old, or she may have been mated without the owner knowing. Sometimes animals come into heat without showing any signs. This is called a “silent heat” and is common in buffalo cows. If the feed is not sufficient or there is a lack of protein, salts or water, the animal can fail to come into heat. You will need to improve the female’s feed to bring it into heat.

Pregnancy in Ruminants
When the animals mate sperm from the male loins with the eggs in the womb. Heat then finishes and the belly of the female enlarges over several months as the young grow during pregnancy.

Heat stops when pregnancy begins. The animal becomes quieter and the belly grows bigger. In milk animals the production of milk will gradually drop.

Length of pregnancy

If male and female animals have been allowed to run together in a large herd it will be difficult to determine the expected time for birth (parturition). If however you do know when a female was mated or given artificial insemination you can determine when she will give birth.

The length of pregnancy differs in different animals.


Length of pregnancy


280 days


320 days


150 days


150 days

There can be a few days difference either way depending on the type, climate, feed and other factors.

Management of the pregnant animal

You must remember that a pregnant animal will need more feed and will benefit from the addition of some grain to the feed towards the end of pregnancy. All pregnant animals should be kept close to home towards the end of the pregnancy and some form of shelter should be provided. They should be watched twice a day for signs that parturition is close. In particular cattle and buffalo need a clean, well ventilated place, preferably with a sand or grit floor on which suitable bedding is placed. Do not keep a pregnant animal constantly tied up or with little room to exercise in. Allow her some freedom in a field or yard each day. She should be observed closely twice a day for signs of parturition.